/Engine/Source/Runtime/Engine/Classes/Components/SkinnedMeshComponent.h
Register an external set of GPU compressed morph targets. These compressed morph targets are GPU only morph targets that will not appear inside the UI and are owned by external systems. Every set of these morph targets has some unique ID.
void AddExternalMorphSet ( int32 LOD, int32 ID, [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FExternalMorphSet](API\Runtime\Engine\Components\FExternalMorphSet) > MorphSet )